| Liaohe Oilfield is mainly in the production of high-viscosity oil. The treatment of high-viscosity oil wastewater, one main problem to be resolved in oil production, is difficult and costly, due to characteristics of wastewater, such as small density difference between water and oil, and severe emulsification. In this paper, a lot of research on the technology of wastewater reuse in thermal recovery boiler was done from laboratory experiment to small-scale, pilot-scale and engineering tests. Results showed that the treated water can be reused in thermal recovery boiler because its quality has reached design requirements of thermal recovery boiler. This technology can make good use of source and temperature of the high-viscosity oil wastewater, recover energy, prevent the pollution to water bodies, and eventually realize the reclamation of wastewater. Consequently, this new technology has high application value.Oil-removal system is basic and key in the whole treatment process of high-viscosity oil wastewater. Oil-removal effect depends on efficient water-purification chemicals. Through laboratory experiments, demulsifying agent TJ-1 and flocculants P-3, which are efficient in wastewater treatment of Huansilian, Du 84, Xingyilian of Liaohe Oil Field, were successfully developed. Moreover, their dosages were optimized.Small-scale tests were carried out at Huansilian, Liaohe Oil Field. The oil-removal effect of regulation tank was strengthened, after the inclined-plane oil separation and floatation pretreatment to further remove oil and suspended matter, wastewater was treated by the efficient bioreactor to reduce COD. The results indicated that:A lot of biological film in efficient bioreactor plays an important role in the removal of COD in high-viscosity oil wastewater. Floatation agent TF-1 serves as a good regulator of influent quality. When the dosage of TF-1 was 12.5～15 mg/L, the removal rate of oil was above 98%, and that of suspended matter and COD were both above 96%. After the treatment, the water appeared clear and transparent. When the dosages of demulsifying agent and flocculants were 75～100mg/L and 2～4mg/L respectively, the value of GT was in the range of 104～105. After the treatment of inclined-plane oil separation and floatation, the water became clear and transparent; the content of oil was 1～2 mg/L, and that of suspended matter was about 2mg/L. The COD in treated water from floatation pool and efficient bioreactor was relatively stable. Besides, the COD in treated water from floatation pool was basically in the range of 200～300mg/L, and its average value was 261mg/L, while the COD in treated water from efficient bioreactor was less than 100mg/L, and its average value was 77.6mg/L. Both of them had met the national emission standards. And this COD treatment process is a new one in wastewater treatment of high-viscosity oil.During pilot-scale tests at Huansilian in advanced treatment of high-viscosity oil wastewater, a complete series of process technology gradually took shape, reaching the recovery and discharge standards. The optimum running parameters were fixed during preceding pilot-scale tests in oil-removal system, forming suspended-matter removal technology and efficient flotation technology after oil-removal. The results showed that when the optimal dosages of demulsifying agent TJ-1 and flocculants P-3 were 50～65mg/L and 0.5～1.0mg/L separately, the average removal rates of oil, suspended matter and COD reached 96.8%,89.6% and 93.3% respectively. In general, when the content of oil in source water increases by 100mg/L, in order to reach the same effect, the dosage of demulsifying agent TJ-1 must increase correspondingly by 10mg/L. Compared with P-3, TJ-1 has greater impact on the treatment effect. The most preferable reflux ratio of efficient flotation separator was 60% approximately; the generated gas-soluble water was milky liquid, and the diameter of bubble was very small. When the dosage of flotation agent TF-1 was the optimal value 10-15mg/L, the removal rates of oil, suspended matter and COD reached 97.7%,83.7% and 37.1% separately in efficient flotation separator. Besides, the oil, suspended matter contents and COD in its treated water were 0.65mg/L,32.0mg/L and 302.6mg/L respectively. The results had met the requirements of supplying water for late biological treatment system and softening system.The removal of hardness, silica, total iron, oil and suspended matter was studied in pilot-scale tests of softening system. The running technical parameters of major equipments were fixed in the tests, forming a set of silica-removal, fine filtration, weak-acidic cation softening technologies. The results indicated that the optimum dosages of lime and magnesium chloride were 300～600mg/L and 200mg/L respectively; the best pH range was 8.5～9.5. The sodium hydroxide softening removed hardness and silica effectively, having similar effects with lime softening. Besides, dosage increase of sodium hydroxide didn't lead to hardness increase of effluent water from coagulation tank. What's more, sludge in sodium hydroxide softening treatment was only one-fifth of that which accounted for 5%-7% of total wastewater in lime softening treatment. Effluent water from floatation pool and coagulation tank was filtrated respectively in dual-media filter, and the results showed that the filtration cycle of water from floatation was 24h, while that of water from coagulation was 32h. After the treatment by lime softening, silica removal with magnesium compound and the strong-acid sodium ion exchange resin, the effluent water from floatation pool had come up to standards of water supply to thermal recovery boiler.This technology of wastewater treatment has been in engineering application at Hanxiling Oil Plant of Liaohe Oil Field. The quality of treated wastewater has met the recovery standards of thermal recovery boiler.
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